Portable communication devices are becoming an increasingly prevalent part of everyday life. Examples of such devices include, but are not limited to, mobile and cordless phones, two-way radio systems and messaging devices. Typically, these devices operate on the power stored in the attached batteries. During charging of the attached batteries by a separate charger system, most portable communication devices are programmed to continue to perform their functions in the usual manner.
A portable communication device can include a display screen, which displays information about the device to a user. The information can be, for example, the date or time, a communication network of the communication device, the battery charge status, and the like.
In most modern communication devices, such as mobile or cellular telephones, the device contains circuitry and firmware to perform the battery charging while the battery is attached to the device. The ‘battery charge’ status displayed on the display screen is controlled by the device; and during the charge process the device can monitor the charge status and, thereby control the battery display, changing the display as the battery is charged. Unless the battery is fitted with a means of digitally monitoring (i.e. coulomb counting, and the like.) the remaining capacity in the battery, portable communication devices typically detect battery charge status by monitoring the battery voltage.
If the device does not have the ability to communicate with the battery to read a coulomb counter, the communication device can monitor the battery voltage. However, the voltage displayed by a battery under charge is different from that of a battery under load or at rest. When an external charger is connected to a portable communication device which does not have an embedded charger to charge the attached battery, the information displayed on the screen of the portable communication device may substantially differ from the actual battery capacity. For example, a two-way radio using a voltage-based fuel gauge may indicate a “battery low” status on the display screen, even when the battery is in the process of being charged. This may cause inconvenience for the user of the two-way radio system.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated, relative to other elements, to help in improving an understanding of the embodiments of the present invention.